I'm happy to help. I've never heard of Dr. F but this thread caught my eye. I have done some thinking about math pedagogy just for my own amusement, though. Mostly, I inflict my theories on my mom, who says that she has some kind of inability to learn algebra.

My mom is a very smart lady and she was a whiz at arithmetic in school. Geometry proofs were intuitive for her and she is a logical thinker. Somehow, she says algebra just doesn't stick in her brain. She can listen to someone explain a problem and it makes perfect sense at the time but she can't reproduce it on her own. I have always wondered if it is just a matter of finding the right way to explain it to her or if she truly has some kind of math disability. I often wish I could do experiments on her <rubbing hands together>....